Ohio Republican Sen. Rob Portman took a terrific, brave step in announcing his support for same-sex marriage, citing the example of his gay son. But here's the missing piece in the current gay rights debate: When Portman's son graduates from Yale, no federal law will prevent an employer from denying him a job because of his sexual orientation. If Will Portman or a classmate came out of the closet after being hired, they could be fired for being gay.

Really? you may ask. If so, you're not alone in your incredulity. Polls show that nine in 10 Americans believe that such basic anti-discrimination protections are already in place.

They're not. The federal law that prohibits employers from discriminating against workers based on race, gender or religion does not extend to sexual orientation. So a company that doesn't want gay employees can refuse to hire them, decline to promote them, pay them less, ignore their being harassed or fire them for being gay -- without fear, in more than half the states, of legal consequences.

Currently, 21 states and the District of Columbia prevent employers from discriminating on the basis of sexual orientation. (In 16 states and in D.C., the protections extend to transgender employees.) In addition, most major employers -- 434 of the Fortune 500 companies, according to the Human Rights Campaign -- have nondiscrimination policies that cover sexual orientation.

All to the good, yet this leaves millions of gay and lesbian Americans without basic workplace protections. And despite extraordinary strides in acceptance, those protections remain essential.

For example, when Harvard University researcher Andras Tilcsik sent two fictitious resumes for 1,800 entry-level, white-collar job openings, the resume that listed the applicant's role as treasurer for a gay campus organization was far less likely to secure a callback interview than the equivalent resume that substituted experience in the "Progressive and Socialist Alliance."

The size of the callback gap showed distinct regional variation among the seven states studied. In California, Nevada, Pennsylvania and New York, there was no statistical difference between gay and heterosexual applicants. By contrast, in Texas, Florida and Ohio, the discrepancy was huge; in Texas, for instance, the heterosexual resumes were more than three times as likely to receive follow-up requests than the gay resumes.

Notably, in places where state or local laws prohibited discrimination on the basis of sexual orientation, those with gay resumes were twice as likely to be called back as in jurisdictions with no legal protections.

The federal legislation that would extend legal protections, the Employment Non-Discrimination Act (ENDA), enjoys large public support -- indeed, far greater public support than does same-sex marriage. Polling of likely 2012 voters by the Center for American Progress showed nearly three-fourths supporting protections from workplace discrimination. Even among voters with an unfavorable view of gay people, half supported workplace protections.

A version of the law failed in the Senate by a single vote in 1996; it passed the House in 2007. Yet ENDA in recent years has taken a legislative and public relations back seat to ending the ban on gays in the military and extending marriage equality. "It's the forgotten issue," said Tico Almeida, president of Freedom to Work, a gay-rights group that lobbies for workplace protections.

President Barack Obama has unfortunately resisted issuing an executive order that would prohibit federal contractors from discriminating against gay workers -- a move that would cover nearly one-fourth of the workforce because of the scope of federal contracts. Maybe this was smart politics before his re-election, but it's hard to see an excuse now.

Meanwhile in the Senate, Iowa Democrat Tom Harkin has promised that his Health, Education, Labor and Pensions Committee will take up ENDA this year. Majority Leader Harry Reid should commit to a floor vote, and counting to 60 is not impossible.

Getting the measure through the House -- especially with protections for transgender workers -- will be a tougher sell. But do Republicans really want to position themselves as the party of intolerance? One data point: In the latest Washington Post-ABC News poll, more than half of Republicans ages 18 to 49 expressed support for same-sex marriage. Another sign of generational shift: Wisconsin Republican Rep. Paul Ryan voted for ENDA in 2007.

The movement for marriage equality is enormously important; its trajectory toward success is nothing short of astonishing. Yet no American should be asked to choose between the right to marry and the right to work. Every American, regardless of sexual orientation, is entitled to both.